Conveyor belt filter devices of the kind mentioned above are also called paternoster filter rakes and are primarily used to mechanically clean flowing sewage in sewers formed for this purpose. The sewage flows through the filter elements, and the filter elements remove the filtered matter, which cannot pass through the filter screens, from the sewer. The structure of the filter belt formed by filter elements that are connected to one another and are connected via flexible drive means that are attached on either side of the filter elements leads to the necessity of providing a gap between the individual filter elements that allows relative mobility in particular because of the required relative mobility of the filter elements in the deflection areas. In order to not reduce the effectiveness of sewage filtering by the filter gap, which is formed between the filter elements and through which the sewage can flow bypassing the filter elements, it is known to provide a gap seal in the filter gap, said gap seal having a flexible sealing element which is capable of compensating changes in gap width, which occur in particular in the deflection areas.
For instance, a conveyor belt filter device of the kind mentioned above is known from U.S. Pat. No. 7,510,650 B2, in which a gap seal is provided in a gap formed between opposing filter element edges, said gap seal having a compressible sealing strip, which is arranged on one of the opposing filter element edges.
In the case of the known gap seal, the sealing strip is formed in such a manner that an elastic deformation portion of the sealing strip completely fills the filter gap. The outer contour of the deformation portion is in direct contact with the filter element edges and is exposed to the flow acting on the filter gap. In order to allow coverage of the entire filter gap both in a straight conveying section of the drive means and in the deflection areas, the deformation portion of the known sealing strip is highly compressed in the straight conveying section, whereas in the deflection conveying section the deformation portion is compressed little by comparison, which means that the deformation portion undergoes extensive flexing in the course of a circulation of the filter belt, which leads to material fatigue and necessitates frequent replacement of the sealing strip.